1. Field of the Invention
This invention relates to a power generation satellite and a transmission antenna apparatus in a space photovoltaic generation system in which the sunlight is received and electric power is generated in space and is transmitted through space by a microwave and is accumulated at a power base for use as electric energy.
2. Description of the Related Art
Power generation systems using sunlight include a solar battery as a small scale, a photovoltaic generation panel installed on a building, intended for home use, and the like. The photovoltaic generation on the ground is not always good in efficiency because of atmospheric attenuation of sunlight and lightness and darkness in day and night on the principle. As the photovoltaic generation in space, a solar panel mounted on an artificial satellite is well known and using the solar panel, the artificial satellite generates electric power required for observation, communications, etc., for achieving its mission. In any way, generated power energy by the solar battery wired to a specific machine is used by the specific machine.
On the other hand, a system for receiving sunlight and generating electric power in space and transmitting the electric power to a specific location, such as a specific point on the earth or in space, is supported by the progression of communication technology, the construction technology of a large-scaled space structure, etc., as the result of the recent space development, and is researched and developed vigorously. As an example of such a space photovoltaic generation system, a system is designed wherein a plurality of power generation satellites are placed in space and at each of the power generation satellites, sunlight is condensed and is converted into electric energy and then a microwave from the electric energy is transmitted to a power base on the ground, etc. The power base has an antenna for receiving the microwave from the plurality of power generation satellites and converts the microwave received at the antenna into a DC and combines.
In the space photovoltaic generation system as described above, to enhance the power generation capability in space, it becomes necessary to place a large number of power generation satellites for transmitting a microwave to the ground in space. At present, generally a phased array antenna is studied as an antenna system of transmission antennas each mounted on each of the power generation satellites. In this case, the assumed size of the antenna is about 200 m to about 1 km in diameter and it is considered that the required number of element antennas reaches several ten millions to several hundred millions. Further, to adjust the phase of an output wave from the phased array antenna, as many transmitters as the number similar to the number of element antennas become necessary, and it is very difficult to manufacture a large-sized phased array antenna about 200 m to about 1 km in diameter as the transmission antenna in the space photovoltaic generation system because an extremely large number of element antennas and an extremely large number of transmitters are required; this is a problem.
It is therefore an object of the invention to provide a power generation satellite and a transmission antenna apparatus in a space photovoltaic generation system having transmission antennas for making it possible to decrease the required number of element antennas and the required number of transmitters wherein electric power generated from sunlight in space is converted into a microwave and then the microwave is transmitted to a power base.
According to the invention, there is provided a power generation satellite having a light condensing optical section, a photoelectric conversion section, a plurality of transmitters, and a transmission antenna. The light condensing optical section condenses sunlight in space. The photoelectric conversion section receives light condensed in the light condensing optical section and generating electric energy. The plurality of transmitters generates microwaves from the electric energy generated by the photoelectric conversion section. The transmission antenna sends the microwaves generated by the transmitters to space. The transmission antenna includes an array antenna having an element antenna for emitting the microwave and a reflecting mirror antenna for reflecting the microwave emitted from the array antenna.
Also, according to the invention, there is provided a transmission antenna apparatus having a photoelectric conversion element, a transmitter, and a transmission antenna. The photoelectric conversion element generates electric energy from incident sunlight. The transmitter generates microwave from the electric energy generated by the photoelectric conversion element. The transmission antenna sends the microwave generated by the transmitters to space. The transmission antenna has an array antenna having an element antenna for emitting the microwave and a reflecting mirror antenna for reflecting the microwave emitted from the array antenna. The photoelectric conversion element is placed on a back of the reflecting mirror antenna.